Manufacture of methyl-paramidophenol sulphate



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Patented Feb. 9, 1932 UNITED STATES PATENT OFFICE mrnun M. moxms, or mention, ENGLAND MANUFACTURE OF METHYL-PARAMIbdPHENOI SULPHATE (METOL) This invention relates to the manufacture oi methylparamidophenol sulphate (metol), and more particularly relates to a methodof .manutacturing this substance by the glycin 1 process.

The principal aim of my invention is to provide a process of the above character which gives. a maximum yield and which may be practiced commercially, yielding expeditiously, and with low cost and expense, a chemical of superior and improved quality.

More particularly my invention includes the provision of an improved method of decomposing parahydroxyphenylglycin (glycin) to a recoverable metol base, and a method which minimizes loss of materials; which permits flexibility in temperatures in its practice; which permits the employment of inexpensive and commercial chemlcals; and permits the recovery of the final product by simple and inexpensive methods. Other objects of my invention will be in part obvious and in part pointed out hereinafter.

lnits broader aspect my improved process comprisesthe use of cresylic acid as a means of decomposing parahydroxyphenylglycin (glycin). The cresylic acid and glycin are brought together and subjected to a heat of sufiicient intensity and duration to decom pose the glycin to recoverable metol base without causing the base to be converted to tar or to evaporate, and the heat being of insufficient intensity and duration to cause decomposition of the cresylic acid. The metol base thus formed in the cresylic acid vehicle is readily recoverable in accordance with wellknown methods and practices which are obvious to persons skilled in the art.

The following are examples of how my process may be carried out.

Ewwmple 1.Placetogether in a suitable vessel 5 grs. glycin and grs. cresylio acid,

heating at a temperature of to degrees centigrade until there is no further decomposition of glycin. Then dilute the mixture with about 100 c. c. solvent naphtha, and shake out with 50 c. 0. water containing 2 c. c. 50 Baumsulphuric acid. This divides the mixture into two layers, one comprising the water and metol and the other comprising Application filed. January 29, 1925. Serial No. 5,635.

the cresylic acid and naphtha. After removing the water layer this is boiled with charcoal, filtered and evaporated to dryness. Then wash the residue with alcohol, and metol, the desired final product, is obtained. The cresylic acid is recoverable according to well known practice.

lice-ample 2.-Place together 10 grs. glycin and 100 grs. cresylic acid, and heat at 17 0 to Although the process 1s operative when glycin is added either quickly or slowly to cold cresylic acid, it has been found that the yields are greater when the glycin is added gradually to hot cresylic acid. An extremely high yield has been obtained when theproportion of glycin to cresylic acid was one to twelve and the temperature permanently fixed at deg. C. and the glycin addedevenly over a period of two hours.

The metol base is slightly volatile in cresylic acid. The distillate from the cresyllc acid distillation should contain about of 1% of its volume of metol base. Pure metol base can be completely distilled under high vacuum without any decomposition, but. in the presence of the impurities, which constitute the cause of the 87% yield in the standard decomposition, only (approx) of the base can be distilled before complete decomposition of the stillresidue occurs.

As many changes could be made in the above process without departing from the scope of myinvention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

What I claim is: p

1. A process of the character described, which includes making a mixture of cresylic acid and parahydroxyphenylglycin having the proportion of one part of parahydroxyphenylglycin to approximately-twelve parts of cresylic acid and heating the mixture sufficiently to decompose parahydroxyphenylglycin to methylparamidophenol (base) without decomposing the cresylic acid.

2. A process of the character described, which includes decomposing parahydroxyphenylglycin to methylparamidophenol (base) in a protecting medium comprising cresylic acid, by heating the parahydroxy phenylglycin to from 17 0 to approximately 185 0.

8. The processof producing methyl-paraamidophenol which comprises decomposing parahydroxyphenylglycin to methyl-paradecomposing parahydroxyphenylglycin to monomethyl-para-amidophenol in the presence of a higher phenolic body and then agitating the reaction mixture with an alcoholic solution containing a quantity of sulphuric acid sufficient to convert the monomethyl para-amidophenol to monomethyl-para-amidophenol sulphate.

This specification signed this 81st day of h December, 1924:. r

' ARTHUR W. M. DICKINS.

amidophenol in a protecting medium compara-hydroxyphenylglycin to methyl-paraamidophenol in a protecting medium comprising more than ten parts of a higher henolic body for every part of parahydroxyphenylglycin.

7. The process of producing methyl-paraamidophenol which comprises decomposing parahydroxyphenylglycin to methyl-paraamidophenol in a protecting medium comprising more than ten parts of a cresolfor every part of parahydroxyphenylglycin.

8. The process of producing methyl-para amidophenol which comprises decomposing parahydroxyphenylglycin to methyl-paraamidophenol in a protecting medium comprising more than ten parts of cresylic acid for every part of parahydroxyphenylglycin. v 9. The process of producing monomethylpara-amidophenol sulphate which comprises decomposing parahydroXyphenylglycin to monomethyl-para-amidophenol in the presence of a higher phenolic body and then agitating the reaction mixture with a solution containing a quantity ofsulphuric acid sufficient to convert the monomethyl-paraami sulphate, said solution being a solvent for monomethyl-para-amidophenol and a -nonsolvent for monomethyl-para-amidophenol sulphate.

6 10. The process of producing monomethylpara-amidophenol sulphate which comprises I dophenol to monomethyl-para-amidophenol I 

